PHENOTYPIC CHARACTERIZATION OF LYMPHOCYTIC CELL INFILTRATES INTO THE TESTES OF RATS UNDERGOING AUTOIMMUNE ORCHITIS

Experimental autoimmune orchitis (EAO) was induced in adult Wistar rat s by active immunization with a testicular homogenate (TH) and adjuvan ts. Fifty per cent of the immunized rats developed EAO. Testicular dam age became evident at 50 days after the primary immunization and incre ased in severity at 80 days. Phenotypic characterization of T-cell sub sets (CD4+ and CD8+) and Ia+ cells was performed on cryostat sections of testis obtained from normal rats, rats immunized with adjuvant (con trol group) and rats immunized with TH and adjuvants (experimental gro up) at 50 and 80 days. Labelled cells were only detected in the inters titial area; no labelled cells were observed inside the seminiferous t ubules with any of the monoclonal antibodies used (W3/25, OX-8, OX-6). A significant increase in the numbers of CD4+ and CD8+, as well as of Ia+ cells, were observed in the testis of rats with severe EAO at 80 days after the first immunization. Rats of the same experimental group without testicular damage showed no major differences compared to rat s from the control group, with the exception of a lower number of CD8 cells. Variations in the lymphocyte subsets in lymph nodes draining t he site of immunization showed the opposite pattern to that observed i n the testis. In conclusion, these data suggest the traffic of specifi cally sensitized lymphocytes from lymph nodes to the testis and an act ive role of CD4+, CD8+ and Ia+ cells in the pathogenesis of EAO in the rat.